1. Field of the Invention
The present invention relates to a sheet bundle binding processing apparatus to perform a binding process after collating and stacking sheets on which images are formed at an image forming apparatus in an image forming system, and relates to a sheet bundle binding processing apparatus capable of performing a binding process with a single binding device selected from a plurality of binding devices.
2. Description of Related Arts
In general, there has been widely known, in an image forming system, a post-processing apparatus (finisher) which performs a binding process on sheets with images formed thereon by an image forming apparatus after collating and stacking the sheets on a processing tray. For performing a binding process, there have been known a method to perform a binding process using a staple, a method to perform bonding with pressing to form a section into a corrugation shape, and a method to perform binding on a sheet bundle as forming a cutout portion and folding a side thereof.
A method to perform a binding process using a staple has an advantage that a relatively thick sheet bundle can be bonded reliably without being easily separated. However, the method has a problem for disposal of bound documents such as shredding thereof. A method to perform bonding with pressure deformation has advantages of being environment-friendly due to non-use of binding part such as a steel-made staple and being superior in noise-reduction and power-saving during operation. However, the method has problems, due to bonding weakness thereof, that the number of sheets to be bonded is limited and the bonding is easily released. Therefore, in general, such methods are selectively used for binding a sheet bundle in accordance with these features.
Japanese Patent Application Laid-open No. 2011-190021 (FIGS. 1 and 3) discloses an apparatus which is continuously connected to a sheet discharging port of an image forming apparatus. Here, image-formed sheets are introduced from an introducing path and stacked on a processing tray. A binding process is performed at the processing tray as selectively using either a stapling unit to perform binding with a staple or a press binding unit to perform bonding with pressure deformation, and then, the bound sheets are stored in a stack tray at the downstream side.
In this case, the stapling unit is supported by a guide rail to be movable along an end face of a sheet bundle positioned on the processing tray to provide two types of binding as being multi-binding to perform binding at a plurality of positions at a predetermined interval while moving and corner binding to perform binding at only one position being a corner of a sheet bundle. Further, the press binding unit is structured to bond a sheet bundle with pressure deformation as nipping the sheet bundle with an upper-lower pair of pressurizing faces having convex grooves and concave grooves.
Japanese Patent Application Laid-open No. 2012-025499 (FIG. 2) discloses an apparatus being similar to the above. In this apparatus, a post-processing is selectively performed as performing a binding process using a staple or without using a staple on sheets fed from an image forming apparatus and stacked on a processing tray, and then, the sheets are discharged to a stack tray at the downstream side.
Further, Japanese Patent Application Laid-open No. 2005-096392 (FIG. 3) discloses an apparatus including a stage arranged at a body casing, the stage having a slit-shaped groove to which a sheet bundle is inserted. Here, after sheets fed from an image forming apparatus are collated and stacked on a stack tray, an operator inserts the sheet bundle to the stage so that a binding process is performed thereon with a stapling unit arranged inside the body casing.